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Network Working Group M. Suzuki
Request for Comments: 3033 NTT
Category: Standards Track January 2001
The Assignment of the Information Field and Protocol Identifier
in the Q.2941 Generic Identifier and Q.2957 User-to-user Signaling
for the Internet Protocol
Status of this Memo
This document specifies an Internet standards track protocol for the
Internet community, and requests discussion and suggestions for
improvements. Please refer to the current edition of the "Internet
Official Protocol Standards" (STD 1) for the standardization state
and status of this protocol. Distribution of this memo is unlimited.
Copyright Notice
Copyright (C) The Internet Society (2001). All Rights Reserved.
Abstract
The purpose of this document is to specify the assignment of the
information field and protocol identifier in the Q.2941 Generic
Identifier and Q.2957 User-to-user Signaling for the Internet
protocol.
The assignment, that is specified in section 4 of this document, is
designed for advanced B-ISDN signaling support of the Internet
protocol, especially the B-ISDN signaling support for the connection
that corresponds to the session in the Internet protocol which is
clarified in section 2. This specification provides an indispensable
framework for the implementation of long-lived session and QoS-
sensitive session transfers over ATM.
1. Purpose of Document
The purpose of this document is to specify the assignment of the
information field and protocol identifier in the Q.2941 Generic
Identifier and Q.2957 User-to-user Signaling for the Internet
protocol.
The assignment, that is specified in section 4 of this document, is
designed for advanced B-ISDN signaling support of the Internet
protocol, especially the B-ISDN signaling support for the connection
that corresponds to the session in the Internet protocol which is
clarified in section 2. Needless to say, the purpose of this
specification is not limited to this support, and it should also be
applicable to other purposes.
This specification provides an indispensable framework for the
implementation of long-lived session and QoS-sensitive session
transfers over ATM. Note that this document only specifies the
assignment of the information field and protocol identifier, and that
it may not specify complete protocol that enables interoperable
implementation. This is because it is beyond the scope of this
document and will be specified in a separate document.
2. Session-related ATM Connection
With the development of new multimedia applications on the current
Internet, the demands for multimedia support are increasing in the IP
network, which currently supports best effort communications. In
particular, demands to support QoS guaranteed communications are
increasing with the development of voice, audio, and video
communications applications. And it may also be necessary to
introduce the mechanism that can efficiently transfer the huge volume
of traffic expected with these applications.
The major features of B-ISDN are high speed, logical multiplexing
with the VP/VC, and flexible QoS management per VC, so it is quite
natural to use these distinctive functions of B-ISDN to implement a
multimedia support mechanism in the IP network. The flexible QoS
management and logical multiplexing functions in B-ISDN are the
expected method of implementing the QoS guaranteed communications in
the Internet. And when a long-lived session is supported by a
particular VC, efficient packet forwarding may be possible using the
high speed and logical multiplexing of B-ISDN.
This section clarifies B-ISDN signaling functions that are required
when the session is supported by the VC, for advanced B-ISDN
signaling support of the Internet protocol.
2.1 Long-lived Session Signaling
An example scenario for establishing a VC for a long-lived session is
shown in Fig. 2.1.
IP Router ATM SW ATM SW IP Router
+----+ Default VC +----+
| WS | +------+ UNI +-----+ +-----+ UNI +------+ | WS |
+--+-+ | /->|<------+-\-/-+--------+-\-/-+------>|<-\ | +-+--+
|.....|__/ |===||==| X |========| X |==||===| \__|.....|
| | | / \ | | / \ | | |
+------+ +-----+ +-----+ +------+
A. New session initially forwarded over a default VC.
IP Router ATM SW ATM SW IP Router
+----+ Default VC +----+
| WS | +------+ UNI +-----+ +-----+ UNI +------+ | WS |
+--+-+ | /->|<------+-\-/-+--------+-\-/-+------>|<-\ | +-+--+
|.....|__/ |===||==| X |========| X |==||===| \__|.....|
| |<------+-/-\-+--------+-/-\-+------>| |
+------+ +-----+ +-----+ +------+
New VC is set up
B. New VC is set up for the long-lived session.
IP Router ATM SW ATM SW IP Router
+----+ Default VC +----+
| WS | +------+ UNI +-----+ +-----+ UNI +------+ | WS |
+--+-+ | |<------+-\-/-+--------+-\-/-+------>| | +-+--+
|.....|__ |===||==| X |========| X |==||===| __|.....|
| \-->|<------+-/-\-+--------+-/-\-+------>|<--/ |
+------+ +-----+ +-----+ +------+
New VC
C. Transfer of the long-lived session to a new VC.
Fig. 2.1: Example scenario for establishing a VC for a long-lived
session.
First, a session is multiplexed into the default VC connecting the
routers. Then, if a router detects that it is a long-lived session,
it sets up a new VC for the session. If the new VC is established
successfully, the long-lived session is moved to the new VC.
In this procedure involving an ATM VC setup, the B-ISDN signaling
entity in the called side router must detect that the incoming call
corresponds to a session of the Internet protocol and notify that
fact to the IP layer entity. Based on this information, the IP layer
entity moves the session to the new VC.
Therefore, to implement this signaling procedure, the B-ISDN
signaling must include an session identifier as an information
element. The B-LLI, B-HLI, User-user, and Generic Identifier
information elements are all capable of transferring this
information. Considering the original purposes of these information
elements, the most appropriate one to use is the Generic Identifier
information element.
2.2 QoS-sensitive Session Signaling
The major difference between QoS-sensitive session signaling and
long-lived session signaling is that call setup is not initiated by
the detection of a long-lived session, but is explicitly initiated by
the setup protocol such as RSVP. To implement QoS-sensitive session
signaling using ATM, the ATM network between the routers must forward
not only the session identifier but also the setup protocol.
There are two schemes for forwarding the setup protocol. One is to
multiplex the protocol into a default VC connecting the routers, or
to forward the protocol through a particular VC. In this case, the
QoS-sensitive session and the ATM VC are established sequentially.
The second scheme is to forward the setup protocol as an information
element in the B-ISDN signaling. In this case, the QoS-sensitive
session and the ATM VC are established simultaneously. The latter
scheme has the following advantages compared with the former one.
o Easier to implement.
- Admission control is simplified, because admission control for
the IP and ATM layers can be done simultaneously.
- Watchdog timer processing is simplified, because there is no need
to watch the IP layer establishment and ATM layer establishment
sequentially.
o If the setup protocol supports negotiation, then an ATM VC whose
QoS is based on the result of negotiation can be established.
However, the latter scheme, at least, cannot support a case where a
PVC is used to support a QoS-sensitive session. Therefore, both
procedures should be taken into account.
An example of a message sequence that simultaneously establishes a
QoS-sensitive session and an ATM VC is shown in Fig. 2.2.
IP Router ATM SW ATM SW IP Router
+----+ B-ISDN Signaling +----+
| WS | +------+ UNI +-----+ Setup +-----+ UNI +------+ | WS |
+--+-+ | /->|<------+-\-/--Protocol--\-/-+------>|<-\ | +-+--+
|.....|__/ |===||==| X |========| X |==||===| \__|.....|
| \-->|<------+-/-\-+--------+-/-\-+------>|<--/ |
+------+ +-----+ Data +-----+ +------+
QoS VC
N-CONNECT | |
---------->| | | | | |
|->| SETUP | | | |
| |------------>| | | |
| |<------------| | | |
| | CALL PROC |----------->| SETUP | |
| | | |------------>| |
| | | | |->| N-CONNECT
| | | | | |---------->
| | | | | |<----------
| | | | CONN |<-| N-CONNECT-ACK
| | | |<------------| |
| | | |------------>| |
| | CONN |<-----------| CONN ACK |->|
| |<------------| | | |
| |------------>| | | |
|<-| CONN ACK | | | |
<----------| | | | | |
N-CONNECT | |
-ACK
Fig. 2.2: Example procedure for simultaneous QoS-sensitive session
and ATM VC establishment.
RSVP is currently proposed for the setup protocol and new setup
protocols are likely to be developed in the future. Therefore, to
generalize the discussion, the procedure for the setup protocol in
this example is the general connection setup procedure using
confirmed service.
To implement this signaling procedure, the B-ISDN signaling must
include the User-user information element that the capacity is
sufficient to forward the setup protocol.
3. Overview of the Generic Identifier and User-to-user Signaling
3.1 Overview of the Generic Identifier
The Generic Identifier enables the transfer of identifiers between
end-to-end users in the ATM network, and it is defined in the Q.2941
Part 1 (Q.2941.1) [3] and Part 2 (Q.2941.2) [4] as an optional
information element for the Q.2931 [1] and Q.2971 [2] UNI signaling
protocol. The SETUP, ALERTING, CONNECT, RELEASE, RELEASE COMPLETE,
ADD PARTY, PARTY ALERTING, ADD PARTY ACK, ADD PARTY REJECT, DROP
PARTY, and DROP PARTY ACK messages that are transferred between end-
to-end users in the ATM network may contain up to three Generic
Identifier information elements. The ATM network transfers the
Generic Identifier information element transparently if it contains
no coding rule errors.
The format of the Generic Identifier information element specified in
the Q.2941 is shown in Fig. 3.1.
Bits
8 7 6 5 4 3 2 1 Octets
+-----+-----+-----+-----+-----+-----+-----+-----+
| Information element identifier |
| = Generic identifier transport IE (0x7F) | 1
+-----+-----+-----+-----+-----+-----+-----+-----+
| 1 | Coding | IE instruction field |
| Ext | standard |Flag |Res. | IE action ind. | 2
+-----+-----+-----+-----+-----+-----+-----+-----+
| Length of contents of information element | 3-4
+-----+-----+-----+-----+-----+-----+-----+-----+
| Identifier related standard/application | 5
+-----+-----+-----+-----+-----+-----+-----+-----+
| Identifier type | 6
+-----+-----+-----+-----+-----+-----+-----+-----+
| Identifier length | 7
+-----+-----+-----+-----+-----+-----+-----+-----+
| Identifier value | 8-
= =
+-----+-----+-----+-----+-----+-----+-----+-----+
= =
+-----+-----+-----+-----+-----+-----+-----+-----+
| Identifier type |
+-----+-----+-----+-----+-----+-----+-----+-----+
| Identifier length |
+-----+-----+-----+-----+-----+-----+-----+-----+
| Identifier value |
= =
+-----+-----+-----+-----+-----+-----+-----+-----+
Fig. 3.1: Format of the Generic Identifier information element.
The usage of the first 4 octets of fields is specified in section 4
of the Q.2931.
The Identifier related standard/application field identifies the
standard or application that uses the identifier. Assignment of the
Identifier related standard/application field for the Internet
protocol is as follows. A leading 0x means hexadecimal.
0x03: IPv4.
0x04: ST2+.
0x05: IPv6.
0x06: MPLS.
Note: DSM-CC, H.310/H.321, MPOA, ATM VCC Trunking, AAL2, and
H.323/H.245 are also supported.
A transferred identifier is given by the combination of the
Identifier type, length and value fields, and a Generic Identifier
information element may contain multiple identifiers.
Assignment of the Identifier type field for the Internet protocol is
as follows. A leading 0x means hexadecimal.
0x01: Session.
0x02: Resource.
0x10-0xFD: Reserved for IANA assignment.
0xFE: Experiment/Organization specific.
The maximum length of the Generic Identifier information element is
63 octets.
See the Q.2941.1 and Draft Q.2941.2 for detailed protocol
specifications of the Generic Identifier.
3.2 Overview of the User-to-user Signaling
The User-to-user Signaling enables the transfer of information
between end-to-end users in the ATM network, and it is defined in
Q.2957 [5, 6] and in Q.2971 annex D [2] as an optional information
element for the Q.2931 [1] and Q.2971 [2] UNI signaling protocol.
The SETUP, ALERTING, CONNECT, RELEASE, RELEASE COMPLETE, PROGRESS,
ADD PARTY, PARTY ALERTING, ADD PARTY ACK, ADD PARTY REJECT, DROP
PARTY, and DROP PARTY ACK messages that are transferred between end-
to-end users in the ATM network may contain a User-user information
element. The ATM network transfers the User-user information element
transparently if it contains no coding rule errors.
From the viewpoint of B-ISDN signaling applications, it seems the
Generic Identifier and User-to-user Signaling are similar functions.
But their rules for processing exceptions are not completely the
same, because their purposes are different. The Generic Identifier
is designed for the transfer of identifiers between the c-planes,
while the User-to-user Signaling is designed for the transfer of user
data via the c-planes. Another difference is that the latter
supports interworking with the user-user information element in the
Q.931 N-ISDN signaling, but the Generic Identifier does not. Note
that the ATM network may check the contents of the Generic Identifier
information element, but does not check the contents of the User-to-
user information element.
The format of the User-user information element is shown in Fig. 3.2.
Bits
8 7 6 5 4 3 2 1 Octets
+-----+-----+-----+-----+-----+-----+-----+-----+
| Information element identifier |
| = User-user information element (0x7E) | 1
+-----+-----+-----+-----+-----+-----+-----+-----+
| 1 | Coding | IE instruction field |
| Ext | standard |Flag |Res. | IE action ind. | 2
+-----+-----+-----+-----+-----+-----+-----+-----+
| Length of contents of information element | 3-4
+-----+-----+-----+-----+-----+-----+-----+-----+
| Protocol discriminator | 5
+-----+-----+-----+-----+-----+-----+-----+-----+
| User information | 6-
= =
| |
+-----+-----+-----+-----+-----+-----+-----+-----+
Fig. 3.2: Format of the User-user information element.
The usage of the first 4 octets of fields is specified in section 4
of the Q.2931.
The Protocol discriminator field identifies the upper layer protocol
that uses the user-user information.
The User information field contains the user-user information to be
transferred.
The maximum length of the User-user information element is 133
octets.
See Q.2957, Draft Q.2957 amendment 1, and Q.2971 annex D for detailed
protocol specifications of the User-to-user Signaling.
4. Information Field and Protocol Identifier Assignment
4.1 Assignment in the Generic Identifier Information Element
4.1.1 Use of Generic Identifier
The information field and protocol identifier assignment principle
for the Internet protocol in the Generic Identifier information
element is shown in Fig. 4.1.
Bits
8 7 6 5 4 3 2 1 Octets
+-----+-----+-----+-----+-----+-----+-----+-----+
| Information element identifier |
| = Generic identifier transport IE (0x7F) | 1
+-----+-----+-----+-----+-----+-----+-----+-----+
| 1 | Coding | IE instruction field |
| Ext | standard |Flag |Res. | IE action ind. | 2
+-----+-----+-----+-----+-----+-----+-----+-----+
| Length of contents of information element | 3-4
+-----+-----+-----+-----+-----+-----+-----+-----+
| Identifier related standard/application |
| = IPv4, ST2+, IPv6, or MPLS | 5
+-----+-----+-----+-----+-----+-----+-----+-----+
| Identifier type |
| = Session, Resource, or Experiment | 6
+-----+-----+-----+-----+-----+-----+-----+-----+
| Identifier length | 7
+-----+-----+-----+-----+-----+-----+-----+-----+
| Identifier value | 8-
= =
+-----+-----+-----+-----+-----+-----+-----+-----+
= =
+-----+-----+-----+-----+-----+-----+-----+-----+
| Identifier type |
| = Session, Resource, or Experiment |
+-----+-----+-----+-----+-----+-----+-----+-----+
| Identifier length |
+-----+-----+-----+-----+-----+-----+-----+-----+
| Identifier value |
= =
+-----+-----+-----+-----+-----+-----+-----+-----+
Fig. 4.1: Principle of assignment in the Generic Identifier
information element.
The Identifier related standard/application field is the IPv4, ST2+,
IPv6, or MPLS.
The Identifier type field is the Session, Resource, or
Experiment/Organization specific.
The Identifier value field is assigned to Internet protocol related
information which is identified by the Identifier related
standard/application field and Identifier type field. The following
identifiers are specified.
Std./app. Id type
IPv4 session identifier IPv4 Session
IPv6 session identifier IPv6 Session
MPLS VCID MPLS Resource
Exp./Org. specific IPv4/ST2+/IPv6/MPLS Experiment
As described in section 3.1, the B-ISDN signaling message transferred
between end-to-end users may contain up to three Generic Identifier
information elements. These elements may contain multiple
identifiers. This document does not specify the order of identifiers
when multiple identifiers appear in a signaling message.
This document also does not specify the semantics when multiple
identifiers having the same Identifier type appear in a signaling
message, or when a signaling message contains a Generic Identifier
information element that does not contain identifiers.
When a B-ISDN signaling message containing a Generic Identifier
information element enters an ATM network that does not support the
Generic Identifier, the network clears the call, discards the
information element, or discards the signaling message. (See
sections 4.5.1 and 5.6.8.1 of Q.2931 and section 9.3 of Q.2941.1 for
details.)
To enable reliable Generic Identifier information element transfer,
when the calling party sends a SETUP or ADD PARTY message with up to
three Generic Identifier information elements, the CONNECT or ADD
PARTY ACK message returned by the called party must contain at least
one Generic Identifier information element. The called party may not
respond with the same identifiers received from the calling party.
The calling party should confirm that the response message contains
at least one Generic Identifier information element. This rule
enables identifier negotiation; this document does not specify the
detailed procedure of this negotiation.
4.1.2 IPv4 session identifier
If the Identifier related standard/application field in the Generic
Identifier information element is the IPv4, and the Identifier type
field in the identifier is the Session, the identifier is the IPv4
session identifier. The format of the IPv4 session identifier is
shown in Fig. 4.2.
Bits Octet
8 7 6 5 4 3 2 1 length
+-----+-----+-----+-----+-----+-----+-----+-----+
| Identifier type |
| = Session (0x01) | 1
+-----+-----+-----+-----+-----+-----+-----+-----+
| Identifier length |
| = 13 octets (0x0D) | 1
+-----+-----+-----+-----+-----+-----+-----+-----+
| Source IPv4 address | 4
+-----+-----+-----+-----+-----+-----+-----+-----+
| Destination IPv4 address | 4
+-----+-----+-----+-----+-----+-----+-----+-----+
| Protocol | 1
+-----+-----+-----+-----+-----+-----+-----+-----+
| Source Port | 2
+-----+-----+-----+-----+-----+-----+-----+-----+
| Destination Port | 2
+-----+-----+-----+-----+-----+-----+-----+-----+
Fig. 4.2: IPv4 session identifier.
The Identifier type field is the Session (0x01).
The Identifier length is 13 octets.
The Source IPv4 address, Destination IPv4 address, Protocol, Source
Port, and Destination Port [7, 9, 10] are assigned in that order to
the Identifier value field.
Note: This specific session identifier is intended for use only with
the explicit reservation. If wild card associations are needed at a
later date, another identifier type will be used.
4.1.3 IPv6 session identifier
If the Identifier related standard/application field in the Generic
Identifier information element is the IPv6, and the Identifier type
field in the identifier is the Session, the identifier is the IPv6
session identifier. The format of the IPv6 session identifier is
shown in Fig. 4.3.
Bits Octet
8 7 6 5 4 3 2 1 length
+-----+-----+-----+-----+-----+-----+-----+-----+
| Identifier type |
| = Session (0x01) | 1
+-----+-----+-----+-----+-----+-----+-----+-----+
| Identifier length |
| = 37 octets (0x25) | 1
+-----+-----+-----+-----+-----+-----+-----+-----+
| Source IPv6 address | 16
+-----+-----+-----+-----+-----+-----+-----+-----+
| Destination IPv6 address | 16
+-----+-----+-----+-----+-----+-----+-----+-----+
| Protocol | 1
+-----+-----+-----+-----+-----+-----+-----+-----+
| Source Port | 2
+-----+-----+-----+-----+-----+-----+-----+-----+
| Destination Port | 2
+-----+-----+-----+-----+-----+-----+-----+-----+
Fig. 4.3: IPv6 session identifier.
The Identifier type field is the Session (0x01).
The Identifier length is 37 octets.
The Source IPv6 address, Destination IPv6 address, Protocol, Source
Port, and Destination Port [8, 9, 10] are assigned in that order to
the Identifier value field.
Note: This specific session identifier is intended for use only with
the explicit reservation. If wild card associations are needed at a
later date, another identifier type will be used.
4.1.4 MPLS VCID
If the Identifier related standard/application field in the Generic
Identifier information element is the MPLS, and the Identifier type
field in the identifier is the Resource, the identifier is the MPLS
VCID. The format of the MPLS VCID is shown in Fig. 4.4.
Bits Octet
8 7 6 5 4 3 2 1 length
+-----+-----+-----+-----+-----+-----+-----+-----+
| Identifier type |
| = Resource (0x02) | 1
+-----+-----+-----+-----+-----+-----+-----+-----+
| Identifier length |
| = 4 octets (0x04) | 1
+-----+-----+-----+-----+-----+-----+-----+-----+
| MPLS VCID | 4
+-----+-----+-----+-----+-----+-----+-----+-----+
Fig. 4.4: MPLS VCID.
The Identifier type field is the Resource (0x02).
The Identifier length is 4 octets.
The MPLS VCID [13] is assigned to the Identifier value field.
4.1.5 Experiment/Organization specific
If the Identifier related standard/application field in the Generic
Identifier information element is the IPv4, ST2+, IPv6, or MPLS, and
the Identifier type field in the identifier is the
Experiment/Organization specific, the identifier is the
Experiment/Organization specific. The format of the
Experiment/Organization specific is shown in Fig. 4.5.
Bits Octet
8 7 6 5 4 3 2 1 length
+-----+-----+-----+-----+-----+-----+-----+-----+
| Identifier type |
| = Experiment/Organization specific (0xFE) | 1
+-----+-----+-----+-----+-----+-----+-----+-----+
| Identifier length | 1
+-----+-----+-----+-----+-----+-----+-----+-----+
| Organizationally unique identifier (OUI) | 3
+-----+-----+-----+-----+-----+-----+-----+-----+
| Experiment/Organization specific info. |
= =
| |
+-----+-----+-----+-----+-----+-----+-----+-----+
Fig. 4.5: Experiment/Organization specific.
The Identifier type field is the Experiment/Organization specific
(0xFE).
The first 3 octets in the Identifier value field must contain the
Organizationally unique identifier (OUI) (as specified in IEEE 802-
1990; section 5.1).
4.2 Assignment in the User-user Information Element
4.2.1 Use of User-to-user Signaling
The information field and protocol identifier assignment principle
for the Internet protocol in the User-user information element is
shown in Fig. 4.6.
Bits
8 7 6 5 4 3 2 1 Octets
+-----+-----+-----+-----+-----+-----+-----+-----+
| Information element identifier |
| = User-user information element (0x7E) | 1
+-----+-----+-----+-----+-----+-----+-----+-----+
| 1 | Coding | IE instruction field |
| Ext | standard |Flag |Res. | IE action ind. | 2
+-----+-----+-----+-----+-----+-----+-----+-----+
| Length of contents of information element | 3-4
+-----+-----+-----+-----+-----+-----+-----+-----+
| Protocol discriminator |
| = Internet protocol/application (0x06) | 5
+-----+-----+-----+-----+-----+-----+-----+-----+
| Internet protocol/application identifier | 6
+-----+-----+-----+-----+-----+-----+-----+-----+
| Internet protocol/application related info. | 7-
= =
| |
+-----+-----+-----+-----+-----+-----+-----+-----+
Fig. 4.6: Principle of assignment in the User-user information
element.
The Protocol discriminator field is the Internet protocol/application
(0x06). In this case, the first 1 octet in the User information
field is the Internet protocol/application identifier field.
Assignment of the Internet protocol/application identifier field is
as follows. A leading 0x means hexadecimal.
0x00: Reserved.
0x01: Reserved for ST2+.
0x02: RSVP message.
0x03-0xFD: Reserved for IANA assignment.
0xFE: Experiment/Organization specific.
0xFF: Reserved.
The field that follows the Internet protocol/application identifier
field is assigned to Internet protocol/application related
information that is identified by the Internet protocol/application
identifier field.
When a B-ISDN signaling message containing a User-user information
element enters an ATM network that does not support the User-to-user
Signaling, the network clears the call, discards the information
element, or discards the signaling message. (See sections 4.5.1 and
5.6.8.1 of Q.2931, section 1.9 of Q.2957, and Q.2971 annex D for
details.)
To enable reliable User-user information element transfer, when the
calling party sends a SETUP or ADD PARTY message with a User-user
information element, the CONNECT or ADD PARTY ACK message returned by
the called party must contain a User-user information element. The
called party may not respond with the same user information received
from the calling party. The calling party should confirm that the
response message contains a User-user information element. This rule
enables negotiation; this document does not specify the detailed
procedure of this negotiation.
4.2.2 RSVP message
The format of the RSVP message is shown in Fig. 4.7.
Bits
8 7 6 5 4 3 2 1 Octets
+-----+-----+-----+-----+-----+-----+-----+-----+
| Information element identifier |
| = User-user information element (0x7E) | 1
+-----+-----+-----+-----+-----+-----+-----+-----+
| 1 | Coding | IE instruction field |
| Ext | standard |Flag |Res. | IE action ind. | 2
+-----+-----+-----+-----+-----+-----+-----+-----+
| Length of contents of information element | 3-4
+-----+-----+-----+-----+-----+-----+-----+-----+
| Protocol discriminator |
| = Internet protocol/application (0x06) | 5
+-----+-----+-----+-----+-----+-----+-----+-----+
| Internet protocol/application identifier |
| = RSVP message (0x02) | 6
+-----+-----+-----+-----+-----+-----+-----+-----+
| RSVP message | 7-
= =
| |
+-----+-----+-----+-----+-----+-----+-----+-----+
Fig. 4.7: RSVP message.
The Internet protocol/application identifier field is the RSVP
message (0x02).
The RSVP message [12] is assigned to the Internet
protocol/application related information field. The SETUP message
may contain the RSVP Resv message. The CONNECT message may contain
the RSVP ResvConf message. The RELEASE message may contain the RSVP
ResvErr or ResvTear message.
4.2.3 Experiment/Organization specific
The format of the Experiment/Organization specific is shown in Fig.
4.8.
Bits
8 7 6 5 4 3 2 1 Octets
+-----+-----+-----+-----+-----+-----+-----+-----+
| Information element identifier |
| = User-user information element (0x7E) | 1
+-----+-----+-----+-----+-----+-----+-----+-----+
| 1 | Coding | IE instruction field |
| Ext | standard |Flag |Res. | IE action ind. | 2
+-----+-----+-----+-----+-----+-----+-----+-----+
| Length of contents of information element | 3-4
+-----+-----+-----+-----+-----+-----+-----+-----+
| Protocol discriminator |
| = Internet protocol/application (0x06) | 5
+-----+-----+-----+-----+-----+-----+-----+-----+
| Internet protocol/application identifier |
| = Experiment/Organization specific (0xFE) | 6
+-----+-----+-----+-----+-----+-----+-----+-----+
| Organizationally unique identifier (OUI) | 7-9
+-----+-----+-----+-----+-----+-----+-----+-----+
| Experiment/Organization specific info. | 10-
= =
| |
+-----+-----+-----+-----+-----+-----+-----+-----+
Fig. 4.8: Experiment/Organization specific.
The Internet protocol/application identifier field is the
Experiment/Organization specific (0xFE).
The first 3 octets in the Internet protocol/application related
information field must contain the Organizationally unique identifier
(OUI) (as specified in IEEE 802-1990; section 5.1).
5. Open Issues
The following issues are still remain in this document.
o Generic Identifier support for session aggregation.
Session aggregation support may be needed in a backbone
environment. Wild card style aggregated session identifier may be
feasible. However, before specifying Generic Identifier support
for it, session aggregation model in ATM VCs should be clarified.
o Generic Identifier support for the IPv6 flow label and traffic
classes.
The IPv6 flow label and traffic classes support may be needed in
future. However, currently their semantics are not clear.
6. IANA Considerations
When the Identifier related standard/application field in the
Q.2941.2 Generic Identifier information element is the IPv4, ST2+,
IPv6, or MPLS, numbers between 0x10-0xFD in the Identifier type field
are reserved for IANA assignment. (See section 3.1.) Following the
policies outlined in [14], these numbers are allocated through an
IETF Consensus action.
When the Protocol discriminator field in the Q.2957 User-user
information element is the Internet protocol/application, numbers
between 0x03-0xFD in the Internet protocol/application identifier
field are reserved for IANA assignment. (See section 4.2.1.)
Following the policies outlined in [14], these numbers are allocated
through an IETF Consensus action.
7. Security Considerations
This document specifies the information field and protocol identifier
assignment in the Q.2941 Generic Identifier and Q.2957 User-to-user
Signaling for the Internet protocol, so these do not weaken the
security of the B-ISDN signaling.
In a called party of the B-ISDN signaling, if the incoming SETUP
message contains the calling party number and if it is verified and
passed by the ATM network or it is provided by the network, then it
is feasible to use the calling party number for part of the calling
party authentication to strengthen security.
Appendix. Information Field and Protocol Identifier Assignment for ST2+
This appendix specifies information field and protocol identifier
assignment in the Generic Identifier and User-to-user Signaling for
ST2+. Note that this appendix is NOT part of the standard.
A.1 ST2+ session identifier
If the Identifier related standard/application field in the Generic
Identifier information element is the ST2+, and the Identifier type
field in the identifier is the Session, the identifier is the ST2+
session identifier. The format of the ST2+ session identifier is
shown in Fig. A.1.
Bits Octet
8 7 6 5 4 3 2 1 length
+-----+-----+-----+-----+-----+-----+-----+-----+
| Identifier type |
| = Session (0x01) | 1
+-----+-----+-----+-----+-----+-----+-----+-----+
| Identifier length |
| = 6 octets (0x06) | 1
+-----+-----+-----+-----+-----+-----+-----+-----+
| Stream ID (SID) | 6
+-----+-----+-----+-----+-----+-----+-----+-----+
Fig. A.1: ST2+ session identifier.
The Identifier type field is the Session (0x01).
The Identifier length is 6 octets.
The Stream ID (SID) [11] is assigned to the Identifier value field.
A.2 ST2+ SCMP
The format of the User-user information element for the ST2+ SCMP is
shown in Fig. A.2.
Bits
8 7 6 5 4 3 2 1 Octets
+-----+-----+-----+-----+-----+-----+-----+-----+
| Information element identifier |
| = User-user information element (0x7E) | 1
+-----+-----+-----+-----+-----+-----+-----+-----+
| 1 | Coding | IE instruction field |
| Ext | standard |Flag |Res. | IE action ind. | 2
+-----+-----+-----+-----+-----+-----+-----+-----+
| Length of contents of information element | 3-4
+-----+-----+-----+-----+-----+-----+-----+-----+
| Protocol discriminator |
| = Internet protocol/application (0x06) | 5
+-----+-----+-----+-----+-----+-----+-----+-----+
| Internet protocol/application identifier |
| = ST2+ SCMP (0x01) | 6
+-----+-----+-----+-----+-----+-----+-----+-----+
| ST2+ SCMP | 7-
= =
| |
+-----+-----+-----+-----+-----+-----+-----+-----+
Fig. A.2: ST2+ SCMP.
The Internet protocol/application identifier field is the ST2+ SCMP
(0x01).
The ST2+ SCMP [11] is assigned to the Internet protocol/application
related information field. The SETUP and ADD PARTY messages may
contain the ST2+ SCMP CONNECT message. The CONNECT and ADD PARTY ACK
messages may contain the ST2+ SCMP ACCEPT message. The RELEASE and
DROP PARTY messages may contain the ST2+ SCMP DISCONNECT message.
The RELEASE, RELEASE COMPLETE, ADD PARTY REJECT, and DROP PARTY
messages may contain the ST2+ SCMP REFUSE message.
References
[1] ITU-T, "Broadband Integrated Services Digital Network (B-
ISDN)-Digital Subscriber Signaling System No. 2 (DSS 2)-User-
Network Interface (UNI) Layer 3 Specification for Basic
Call/Connection Control," ITU-T Recommendation Q.2931, September
1995.
[2] ITU-T, "Broadband Integrated Services Digital Network (B-ISDN)-
Digital Subscriber Signaling System No. 2 (DSS 2)-User-Network
Interface Layer 3 Specification for Point-to-Multipoint
Call/Connection Control," ITU-T Recommendation Q.2971, October
1995.
[3] ITU-T, "Broadband Integrated Services Digital Network (B-ISDN)
Digital Subscriber Signaling System No. 2 (DSS 2): Generic
Identifier Transport," ITU-T New Recommendation Q.2941.1,
September 1997.
[4] ITU-T, "Broadband Integrated Services Digital Network (B-ISDN)
Digital Subscriber Signaling System No. 2 (DSS 2): Generic
Identifier Transport Extensions," ITU-T New Recommendation
Q.2941.2, December 1999.
[5] ITU-T, "Stage 3 Description for Additional Information Transfer
Supplementary Service Using B-ISDN Digital Subscriber Signaling
System No. 2 (DSS 2)-Basic Call Clause 1-User-to-User Signalling
(UUS)," ITU-T Recommendation Q.2957, February 1995.
[6] ITU-T, "Stage 3 Description for Additional Information Transfer
Supplementary Service Using B-ISDN Digital Subscriber Signaling
System No. 2 (DSS 2)-Basic Call Clause 1-User-to-User Signalling
(UUS)," ITU-T Recommendation Q.2957 Amendment 1, December 1999.
[7] Postel, J., Ed., "Internet Protocol", STD 5, RFC 791, September
1981.
[8] Deering, S. and R. Hinden, "Internet Protocol, Version 6 (IPv6)
Specification", RFC 2460, December 1998.
[9] Postel, J., "User Datagram Protocol", STD 6, RFC 768, August
1980.
[10] Postel, J., Ed., "Transmission Control Protocol", STD 7, RFC
793, September 1981.
[11] Delgrossi, L. and L. Berger, Ed., "Internet Stream Protocol
Version 2 (ST2) Protocol Specification - Version ST2+", RFC
1819, August 1995.
[12] Braden, R., Ed., "Resource ReSerVation Protocol (RSVP) - Version
1 Functional Specification", RFC 2205, September 1997.
[13] Nagami, K., Demizu, N., Esaki, H., Katsube, Y. and P. Doolan,
"VCID Notification over ATM link for LDP", RFC 3038, January
2001.
[14] Narten, T., and H. Alvestrand, "Guidelines for Writing an IANA
Considerations Section in RFCs", BCP 26, RFC 2434, October 1998.
[15] P. Newman, T. Lyon, and G. Minshall, "Flow Labelled IP: A
Connectionless Approach to ATM," Proc. IEEE Infocom, March 1996.
[16] S. Damaskos and A. Gavras, "Connection Oriented Protocols over
ATM: A case study," Proc. SPIE, Vol. 2188, pp.226-278, February
1994.
[17] ITU-T, "Integrated Services Digital Network (ISDN) Overall
Network Aspects and Functions ISDN Protocol Reference Model,"
ITU-T Recommendation I.320, November 1993.
[18] ITU-T, "Digital Subscriber Signaling System No. 1 (DSS 1)
Specification of a Synchronization and Coordination Function for
the Provision of the OSI Connection-mode Network Service in an
ISDN Environment," ITU-T Recommendation Q.923, February 1995.
Acknowledgments
I would like to thank Kenichi Kitami of the NTT Information Sharing
Lab. Group, who is also the chair of ITU-T SG11 WP1, Shinichi
Kuribayashi of the NTT Information Sharing Platform Labs., Hiroshi
Yao and Takumi Ohba of the NTT Network Service Systems Labs., and
Noriyuki Takahashi of the NTT Information Sharing Platform Labs., for
their valuable comments and discussions.
And I would also like to thank the active members of IETF, ITU-T, and
ATM Forum, especially Joel Halpern of Newbridge Networks, Andrew
Malis of Ascend Communications, George Swallow and Bruce Davie of
Cisco Systems, Rao Cherukuri of IBM, Rajiv Kapoor of AT&T, Greg Ratta
of Lucent, Kaoru Kenyoshi of NEC, Hiroto Uno of Hitachi, Hiroshi
Esaki and Kenichi Nagami of Toshiba, and Noritoshi Demizu of NAIST
for their valuable comments and suggestions.
Also, this specification is based on various discussions during the
ST2+ over ATM project at the NTT Multimedia Joint Project with
NACSIS. I would like to thank Professor Shoichiro Asano of the
National Center for Science Information Systems for his invaluable
advice in this area.
Author's Address
Muneyoshi Suzuki
NTT Information Sharing Platform Laboratories
3-9-11, Midori-cho
Musashino-shi, Tokyo 180-8585, Japan
Phone: +81-422-59-2119
Fax: +81-422-37-7691
EMail: suzuki.muneyoshi@lab.ntt.co.jp
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